Big Cash Prize For Untangling Shredded Paper

So, you think Will's puzzles are tough? How about trying to reconstruct a document that's been through a shredder? That was the task offered to software developers this fall by the Pentagon's research arm DARPA, the Defense Advanced Research Projects Agency. DARPA shredded some documents, scanned the shreds, and then asked computer engineers to come up with software that could put things back together.

The winner of the $50,000 prize was a team headed by California software developer Octavio Good. And Mr. Good joins here us in the studio.

Hello.

OCTAVIO GOOD: Hello.

CORNISH: So, this task seems kind of impossible.

(SOUNDBITE OF LAUGHTER)

CORNISH: So explain how did your program work? How did you put back together all 10,000 pieces?

GOOD: It looked impossible from the start. I didn't think anyone would pull it off. DARPA gave us about five different puzzles, meaning five different pieces of paper that were shredded basically in different ways. But the approach that we took, it's kind of like playing a puzzle where you see a bunch of pieces around, you click on one of them and the computer helps you out. The computer recommends what it thinks the top matches are, and then you can place the puzzle like that.

CORNISH: And, as you said, each piece of paper that was shredded had a puzzle in it, right? And there was sort of an overall theme. And the theme was based on the old Mad Magazine series "Spy versus Spy, is that true?

GOOD: Yes. When we were getting it together, it seemed like they were going with a kind of Cold War spy theme. Seemed like they were having some fun with the puzzle.

CORNISH: Seems like we should have guessed that, huh? Like...

(SOUNDBITE OF LAUGHTER)

CORNISH: ...something like maybe they should've made it harder in a way. Although, I see that 9,000 participants kind of downloaded the software. But it was very difficult, not that many groups were able to come up with a plan, right?

GOOD: Yeah, I think it was incredibly difficult. And we had a team of probably eight people, when you count everybody. And we were working nonstop outside of work hours for a month.

CORNISH: What's the practical application here?

GOOD: I think what we created is, is a proof of concepts. I like to think of it as setting the bar for where the security is of these shredders. A lot of security can be cracked; the lock on your front door can probably be picked and it's good to know that. You don't want to turn a blind eye to that âcause then you can base your security decisions on that.

And what we've done here is we've managed to shred, you know, certain levels of difficulty shredders. And we can kind of say, OK, this is what's un-shreddable and this is what's not un-shreddable. And there's definitely shredders out there that you can not put back together.

CORNISH: Oh, good. And he's probably not the one that I have at my house, right, I'm assuming?

(SOUNDBITE OF LAUGHTER)

GOOD: If you've got a cheap one for your house there's a chance that it could be put back together.

CORNISH: But what's safe then?

GOOD: So, it turns out in some ways - I'm not an expert at this and I've never actually touch a shredding machine in my life.

(SOUNDBITE OF LAUGHTER)

GOOD: They said what we had was a level four security shredder - whatever that means - and we managed to put that back together, although it was incredibly challenging. So if you have something better than that, I think your documents are safe.

CORNISH: Software developer Octavio Good, thanks so much for speaking with us.